Add an "lga" pseudoinstruction for GOT loads even in non-PIC #50
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jrtc27
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This mirrors lla and is always GOT-relative, allowing an explicit request to use the GOT without having to expand the instruction. This then means la is just defined in terms of lla and lga in the assembler, based on whether PIC is enabled, and at the codegen level we replace la entirely with lga since we only ever use la there when we want to load from the GOT (and assert that to be the case). See riscv-non-isa/riscv-asm-manual#50 Reviewed By: asb, MaskRay Differential Revision: https://reviews.llvm.org/D107278
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Following is a duplicate of @jrtc27's proposal from riscv/riscv-isa-manual#539.
This is useful for cases where compilers and/or assembly writers want to force the use of a GOT. For example, this could be used to address [1], but more generally it's a useful thing to have, and is a strange hole in the set of pseudoinstructions provided.
Whilst here, alter the description of "la" to not mention absolute. All addresses are absolute, but highlighting it for "la" specifically is confusing as it potentially implies that it's using an absolute lui/addi sequence rather than a PC-relative sequence.
[1] riscv-non-isa/riscv-elf-psabi-doc#126
I have not yet created patches against riscv-asm-manual and riscv-elf-psabi-doc. However, those are already outdated and only mention
lawithoutlla. Defininglgawill also make it far less confusing to fix that; then,llaandlgacan be documented individually, withlasimply saying it's equivalent to the relevant one depending on -fPIC.The text was updated successfully, but these errors were encountered: